Biological macromolecules do not function in isolation: typically they function as part of a larger assembly in vivo. The atomic structures of some such assemblies are being uncovered: myosin S1 complexed with tropomyosin and filamentous actin, tubulin, protein:DNA complexes and others. The enormous sizes of these systems and the limited resolution of the atomic coordinates prohibit the use of conventional molecular dynamics techniques to glean insight into their overall mechanical and dynamical properties. For these reasons, normal modes analysis (NMA) is the tool of choice in characterizing the mechnical and dynamical properties of such ensembles. To date, NMA of isolated protein and DNA polymers have been carried out successfully. However, the inclusion of multiple molecules, such as protein dimers and trimers, requires special tools to permit the diagonalization of the eigenvalue equations. Over the last year, we have developed software to compute the equilibrium vibrational properties of protein assemblies. We reproduce the soft, slow collective modes of G-actin bound with ADP and a tighly bound cation obtained using other approximate techniques. The software permits the identification of the softest modes of the ternary G-Actin:ADP:Ca system, with 1400 degrees of freedom, 40,000 nonbonded interactions, in 45 CPU minutes on a single R6000 processor. Visualization of the slow modes of these assemblies using the animation tools of DataExplorer permits graphic insight into the nature of the elasticity, deformability, and dynamics of these massive macromolecular assemblies. Working together with CTC we have produced a video showing some of the slow vibrational motions characterstic to filamentous actin. In future, we will utilize the software to examine the vibrational spectra of other large muscle proteins and muscle protein complexes.